Liquid rosin sizes containing anti-stratifying agent



LIQUID ROSIN SIZES CONTAINING ANTI-STRATIFYING AGENT William C. Hopkins,Valdosta,

Jr., South Charleston, Cyanamid Company, of Maine Ga., and John G.Senese, W. Va., assignors to American New York, N. Y., a corporation NoDrawing. Application February 25, 1954 Serial No. 412,636

5 Claims. (Cl. 106-438) Rosin sizes have their principal use in themanufacture United States Patent 0 of paper. These sizes aremanufactured on a large commercial scale by heating a natural ormodified rosin above its melting point, forming a hot caustic solutionfrom Water and an alkali metal alkali such as potassium or, morecommonly, sodium hydroxide or carbonate, and reacting the alkalisolution with the rosin. The rosins referred to are organic acids.Neutralization of these acids by the caustic takes place within a fewhours, the product being a viscous soap dispersion. In this process, theamount of water employed is controlled so that the size contains betweenabout 50% and 80%85% of size solids, on the one hand to avoid sizes sodilute that they cannot be shipped economically, and on the other handto avoid sizes so concentrated and, therefore, viscous that they cannotbe pumped.

The amount of alkali employed in this manufacture is at least about 60%of that requiredfor complete neutralization so that the size contains upto about 40% of free rosin acids, based on the weight of the solidstherein, a lower amount of alkaliyielding a size which contains so muchfree rosin acids that it cannot be successfully diluted for applicationto paper. On the other hand, the amount of alkali may be sufficient tocompletely neutralize the rosin, and this yields satisfactory sizes.

In commercial practice, liquid rosin sizes generally contain between 60%and 80% of size solids by weight,

thus minimizing shipping costs while providing a product having apumpable viscosity at a temperature of about 60-70" C., this being thestandard temperature at which sizes are handled within paper mills.Moreover, suflicient alkali is used to cause at least 95 %75neutralization of the rosin, this amount insuring that the rosinpossesses excellent dilutability in water while maintaining consumptionof alkali and the viscosity of the product at minimum practical values.

Frequently, liquid rosin sizes are stored by the manufacturer beforethey are shipped in tank cars, and these sizes are further stored bypaper manufacturers before use. It is known that during these periods ofstorage liquid rosin sizes of the commercially practicable types Imentioned, that is, sizes containing from about 5% to of free rosinacids and about 60% to 80% of solids, stratify on storage and separateinto two layers. The

bottom layer is more viscous than the upper layer. Hence,

when a liquid rosin size has been prepared of maximum pumpableviscosity, allowance being made for the increase in viscosity whichnormally takes place on agmg, storage of the sizeresults in separationof a bottom layer which A further disadvantage is that the upper layeris usually 2,873,203 Patented Feb. 10, 1959 darker in color than thelower layer, and this introduces a problem of color control in themanufacture of paper.

Stratification of liquid rosin size often becomes evident in thelaboratory in 3-5 hours and, in the case of rosin stored in largecommercial tanks, in about 3 days. The phenomenon is not spontaneouslyreversible and homogeneity can be obtained only by thorough mixing ofthe contents of the tank.

The discovery has now been made that liquid rosin sizes of thecomposition mentioned containing a small amount of sodium chloride donot stratify or otherwise separate on storage. The stratification isinhibited by the presence therein of between about 0.7% and 2% by weightof dissolved sodium chloride based on the weight of solids in the sizeand substantially completelyinhibited by the presence therein of betweenabout 2% and 5% by weight of-dissolved sodium chloride based on theweight of solids in the size. It has further been found that separationof the sizes into phases takes place when more than about 5% of sodiumchloride is present, the sodium chloride in this instance acting to saltout the rosin soap resulting also in an actual increase in viscosity ofthe size.

. From the foregoing it will be seen that the subject matter of thepresent invention comprises a liquid rosin size of about 5% to 25% freerosin acids content containing about 60% to size solids by weight, saidsize being inhibited against Stratification on storage by the presenceof an effective amount between about 0.7% and 5%, based on the weight ofthe solids, of sodium chloride dissolved therein, the amount of saidsodium chloride being insufiicient to salt out said size.

The amount of sodium chloride which should be present within the rangementioned varies with the type of rosin employed, the solids content ofthe size, the amount of free rosin acids in the size, and thetemperature of the size. As a result, the minimum effective amount canbest be determined in each instance by laboratory trial. In general,with regard to liquid rosin sizes of the composition mentioned, we havefound that. fortified rosin sizes of low solids content but containingan intermediate amount of free rosin acids show the greatest and mostrapid stratification, and that with regard to these sizes, highertemperatures favor Stratification. For example, a fortified rosin sizecontaining 60% or 70% solids and 15% of free rosin acids is particularlyprone to stratify and requires somewhat more sodium chloride forstabilizationat the upper normal storage temperature of 80 C. than doesordinary rosin size containing 80% solids and 15% free rosin acids atthe lower normal storagetemperature of 50 C.

In place of sodium chloride, no reason is known why other alkali metalhalides such as sodium bromide and sodium iodide as well as thecorresponding potassium salts are not also effective, and these saltsare therefore included within the broad scope of the present invention.

Because of its ready availability and the excellent results which itaffords, sodium chloride is preferred, and in commercial practice commonrock salt has proved entirely satisfactory.

In addition toinhibiting stratification it is a most important advantageof the present invention that the presence of sodium chloride verygreatly decreases the viscosity of the sizes often to only a smallfraction of the values which they would otherwise possess.

ture falls, and since rosin sizes are normally stored in heated storagetanks, this means that rosin in such tanks can be stored at lowertemperatures than would otherwise be the case. It is the customarypractice of paper .mills to store rosin size in tanks maintained at atemperature between about 60-70 C. The presence of sodium Since the tviscosity of liquid rosin sizes increases as their temperachloridepermits the same sizes' to be stored at a temperature about20 C. lowerwithout increase inv viscosity, .thus permitting substantial economy inthe heat supplied.

It is a further advantage that the sodium chloride does Example 1 'Theefiiect of sodium chloride ininhibiting stratification and decreasingthe viscosity of a liquid fortified rosin size is illustrated asfollows.

A I 15,000 pounds of M gra e gum rosin to an ma i ii ih e iffifiiz vi ili iii {82 221 1 2 zi g fggi slowly adding 600 pounds of malercanhydrrde. Reacp i D tion of the maleic anhydride was complete in 3hours creases rapldly 1n viscosity during the course of about at about Cthe product being fortified rosin the ifirst seven days, the viscosityat that time often being containing the A1 def rosin maleic anhydrideseveral times that of the initial viscosity of the material. ProductThereafter the viscosit of the size enerall remains at or near the highvalu reached towirds the end of the In Separat? vessel 1800 Pounds ofsodlum hydrpxlde first week of storage It is a further most importantadwas dlssolved 5 7 9 pomllds of wlater 5 t heated to 95 e mo ten maeate rosin an e n a h a no 0" s dlum chloride 1s a ermanent die t lfe taib ilized sii es ot the present inventi hn having hot causuc Sohmonwere Separately but slmultanecusy a much lower viscosity during andafter this period than ;2 :5 :2 i gf r j g i g ifigg 52322 correspondingsizes containing no sodium chloride. ag

In the manufacture of the liquid rosin sizes to which the caustlcCmFPIetC m 2 hours The resulting S126 the present invention is directed,numerous forms of 1:3 23% 2 aclds content of 15% and a sohds conrosinare currently employed and include gum rosin, A wood rosin, and tall oilrosin, the latter being a new de- T Your i 1 a f 2:12 g gf g sdvelopment in the rosin field for which standards have 0 one P e a e cbeen promulgated by the Department of Agri aqueous sod um chlorldesolutron to provide 0.7% of culture Moreover resins may be employedwhich 25 sodium chloride based on the weight of the solids therein. taina minor amourit, e. g. 10% to 40% by weight of the To the Second. hcontrol Sample) was ldF an equal Diels-Alder adducts formed by reactinga naturallyvolume of delomzed t To h remammg sampies occurring rosinwith maleic anhydride or similar material. ii saglraied iodmm chlondfisolutloifio provllde These rosins and the sizes prepared therefrom,generally sodmm c on e 6 t 6 y? 8 g fi respectively termed fortifiedrosins and fortified rosin i? stofed at 8 an 0 Serve perm lea y or Sizesare disclosed broadly in S Patents 2,628; stratification. In addition,small amounts were removed 918 and 2 385 periodically from the controlsample and Sample A and It will mlderstood that liquid rosin Sizes inaddi their viscosity determined at the temperatures noted, the tion tothe foregoing, commonly contain a number of entlre sample belng firstmade homogeneous by stn'rlng other materials. Included are the loweraliphatic alcobefore E Sfnan amounts were wlthdrawn' hols and rosinesters therewith since rosin size may be Stratlficatlon deemed to takeP151Ce when two prepared f rosin estem Moreover, natural resins tlnctlayers of dliferent color could be observed. The contain small amountsof unsaponifiable materials in- P were ratefi an Y Scale 011 Whlcl} 4cluding lignin and stearols. Sizes containing these matelndlcatfis badStratlficatlon, 1 lndlcates p ly slfght rials undergo stratification onstorage and the present 40 Stratification, and 0 indicates no noticeablestratification. invention is advantageously employed therewith. Resultsare as follows:

P t. Viscosity 2 at C. Viscosity 1 at 71 0.

en Sample N 58] Start 4Days 7Days 12 Days Start 4Days 7Days 12 DaysContL- Nil 17, 700 57,000 75. 000 47, 500 2,500 9,500 11, 500 8,400 A 0.5, 000 7,000 17,000 8,500 1,000 1,20 1,800 1, 500 2.0 IIII IIII IIIIIIII IIII IIII IIII IIII gaseil 0111 solids content of size.

en p0 SE5.

The sodium chloride may be introduced at any desirable point in themanufacture of the rosin size. For ex- Stratificatio'n ample, it may bedispersed into the molten rosin itself Sample or may be dissolved in theliquid size subsequent to its 4Days 7Days 12 Days preparation. Since,however, liquid rosin size is normally produced on a very largeindustrial scale it has 60 n] 4 4 4 been found most convenient todissolve the sodium chlog 1 ride in the water in which the alkali metalalkali is dis- 0 0 0 0 solved. In this manner uniform distribution ofthe antistratification agent is most readily effected, and separate 1 Onstorage at 80 0. metering of the agent becomes unnecessary.

These tests show that the presence of 0.7% and 1.25% of sodium chlorideinhibits stratification and that increasing the amount to 2%substantially prevents stratification. The tests further show that only0.7% of sodium chloride causes a sharp reduction in the viscosity of thesize throughout the test. From previous experience it is known that theviscosity of rosin sizes containing 2%5% of sodium chloride is less thanthe viscosity of similar sizes which contain 1.25% of sodium chloride.

Example 2 The effect of increasing amounts of sodium chloride upon thestratification of and viscosity of resin size is illustrated by thefollowing.

A fortified rosin size containing 72.5% solids and 9.6% free rosin wasmade by the method of Example 1, and a control sample and sodiumchloride-containing samples were prepared also as described inExample 1. The initial viscosity of these samples was determined at 71C. The samples were stored at 71 C. for two days and ob served forstratification. Results are as follows, the stratification index beingthat of Example 1.

Stratification at 2 Days Percent N M31 1 Viscosity at 71 0. (ep.)

ssiia Out...

asraaoa weight of said solids, of sodium chloride dissolved therein, theamount of said sodium chloride being insuflicient to salt out said size.

2. A liquid rosin size which is a uniform aqueous dispersion containingfrom about to 80% rosin size solids by weight, and 5% to 25% of treerosin acids based on the weight of said solids, said size being stabilized against stratification on storage by the presence of aneffective amount between 2% and 5%, based on the weight of said solids,of sodium chloride dissolved therein, the amount of said sodium chloridebeing insuflicient to salt out said size.

3. A liquid maleated rosin size according to claim 2.

4. A liquid rosin size which is a uniform aqueous dispersion containingabout rosin size solids by weight, and about 15% free rosin acids basedon the weight of said solids, said size being stabilized againststratifica tion on storage by the presence of an effective amountbetween 2% and 5%, based on the weight of said solids, of sodiumchloride dissolved therein, the amount of said sodium chloride beinginsufiicient to salt out said size.

5. A liquid maleated rosin size according to claim 4.

References Cited in the file of this patent UNITED STATES PATENTS 83,707Gray Nov. 3, 1868 405,269 Menzies June 18, 1889 2,192,488 Reilly Mar. 5,1940 2,213,943 Auer Sept. 10, 1940

1. A LIQUID ROSIN SIZE WHICH IS A UNIFORN AQUEOUS DISPERSION CONTAININGFROM ABOUT 60% TO 80% ROSIN SIZE SOLIDS BY WEIGHT, AND 5% TO 25% OF FREEROSIN ACIDS BASED ON THE WEIGHT OF SAID SOLIDS, SAID SIZE BEINGINHIBITED AGAINST STRATIFICATION ON STORAGE BY THE PRESENCE OF ANEFFECTIVE AMOUNT BETWEEN 0.7% AND 5%, BASED ON THE WEIGHT OF SAIDSOLIDS, OF SODIUM CHLORIDE DISSOLVED THERE, THE AMOUNT OF SAID SODIUMCHLORIDE BEING INSUFFICIENT TO SALT OUT SAID SIZE.